In recent years, a parametric speaker with high directivity to provide sound to a person at a particular position is getting attention. It is expected that the parametric speaker is mounted on an electronic device, such as, a mobile phone, etc to provide a sound signal around a user, etc.
Here, when the parametric speaker is mounted on the electronic device, for example, a mobile phone, etc., it is desired to miniaturize the parametric speaker. However, it is difficult in principle to miniaturize an electro-dynamic electroacoustic transducer with a magnetic circuit. Therefore, it is expected to use an electroacoustic transducer using a piezoelectric vibrator.
In Patent Literatures 1 to 3, there is disclosed an electroacoustic transducer that comprises a plurality of piezoelectric vibrators that are arranged side by side in a direction toward a direction of sound wave emission.    [Patent Literature 1]    Japanese Patent Kokai Publication No. 2003-061194A    [Patent Literature 2]    Japanese Patent Kokai Publication No. 1997-093696A    [Patent Literature 3]    Japanese Patent Kohyo Publication No. 1988-048479A